Commit d0537508 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds
Browse files

[PATCH] kexec: x86_64: add CONFIG_PHYSICAL_START 



For one kernel to report a crash another kernel has created we need
to have 2 kernels loaded simultaneously in memory.  To accomplish this
the two kernels need to built to run at different physical addresses.

This patch adds the CONFIG_PHYSICAL_START option to the x86_64 kernel
so we can do just that.  You need to know what you are doing and
the ramifications are before changing this value, and most users
won't care so I have made it depend on CONFIG_EMBEDDED

bzImage kernels will work and run at a different address when compiled
with this option but they will still load at 1MB.  If you need a kernel
loaded at a different address as well you need to boot a vmlinux.

Signed-off-by: default avatarEric Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 8a919085

arch/x86_64/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -369,6 +369,17 @@ config X86_MCE_INTEL 
	   Additional support for intel specific MCE features such as

	   the thermal monitor.



config PHYSICAL_START

	hex "Physical address where the kernel is loaded" if EMBEDDED

	default "0x100000"

	help

	  This gives the physical address where the kernel is loaded.

	  Primarily used in the case of kexec on panic where the

	  fail safe kernel needs to run at a different address than

	  the panic-ed kernel.



	  Don't change this unless you know what you are doing.



config SECCOMP

	bool "Enable seccomp to safely compute untrusted bytecode"

	depends on PROC_FS

arch/x86_64/boot/compressed/head.S

+4 −3
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 


#include <linux/linkage.h>

#include <asm/segment.h>

#include <asm/page.h>



	.code32

	.globl startup_32
@@ -77,7 +78,7 @@ startup_32: 
	jnz  3f

	addl $8,%esp

	xorl %ebx,%ebx

	ljmp $(__KERNEL_CS), $0x100000

	ljmp $(__KERNEL_CS), $__PHYSICAL_START



/*

 * We come here, if we were loaded high.
@@ -103,7 +104,7 @@ startup_32: 
	popl %ecx	# lcount

	popl %edx	# high_buffer_start

	popl %eax	# hcount

	movl $0x100000,%edi

	movl $__PHYSICAL_START,%edi

	cli		# make sure we don't get interrupted

	ljmp $(__KERNEL_CS), $0x1000 # and jump to the move routine
@@ -128,7 +129,7 @@ move_routine_start: 
	movsl

	movl %ebx,%esi	# Restore setup pointer

	xorl %ebx,%ebx

	ljmp $(__KERNEL_CS), $0x100000

	ljmp $(__KERNEL_CS), $__PHYSICAL_START

move_routine_end:

arch/x86_64/boot/compressed/misc.c

+4 −3
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 


#include "miscsetup.h"

#include <asm/io.h>

#include <asm/page.h>



/*

 * gzip declarations
@@ -284,7 +285,7 @@ void setup_normal_output_buffer(void) 
#else

	if ((ALT_MEM_K > EXT_MEM_K ? ALT_MEM_K : EXT_MEM_K) < 1024) error("Less than 2MB of memory");

#endif

	output_data = (char *)0x100000; /* Points to 1M */

	output_data = (char *)__PHYSICAL_START; /* Normally Points to 1M */

	free_mem_end_ptr = (long)real_mode;

}
@@ -307,8 +308,8 @@ void setup_output_buffer_if_we_run_high(struct moveparams *mv) 
	low_buffer_size = low_buffer_end - LOW_BUFFER_START;

	high_loaded = 1;

	free_mem_end_ptr = (long)high_buffer_start;

	if ( (0x100000 + low_buffer_size) > ((ulg)high_buffer_start)) {

		high_buffer_start = (uch *)(0x100000 + low_buffer_size);

	if ( (__PHYSICAL_START + low_buffer_size) > ((ulg)high_buffer_start)) {

		high_buffer_start = (uch *)(__PHYSICAL_START + low_buffer_size);

		mv->hcount = 0; /* say: we need not to move high_buffer */

	}

	else mv->hcount = -1;

arch/x86_64/kernel/head.S

+9 −9
Original line number Diff line number Diff line
@@ -248,23 +248,23 @@ ENTRY(_stext) 
	 */

.org 0x1000

ENTRY(init_level4_pgt)

	.quad	0x0000000000102007		/* -> level3_ident_pgt */

	.quad	0x0000000000002007 + __PHYSICAL_START	/* -> level3_ident_pgt */

	.fill	255,8,0

	.quad	0x000000000010a007

	.quad	0x000000000000a007 + __PHYSICAL_START

	.fill	254,8,0

	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */

	.quad	0x0000000000103007		/* -> level3_kernel_pgt */

	.quad	0x0000000000003007 + __PHYSICAL_START	/* -> level3_kernel_pgt */



.org 0x2000

ENTRY(level3_ident_pgt)

	.quad	0x0000000000104007

	.quad	0x0000000000004007 + __PHYSICAL_START

	.fill	511,8,0



.org 0x3000

ENTRY(level3_kernel_pgt)

	.fill	510,8,0

	/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */

	.quad	0x0000000000105007		/* -> level2_kernel_pgt */

	.quad	0x0000000000005007 + __PHYSICAL_START	/* -> level2_kernel_pgt */

	.fill	1,8,0



.org 0x4000
@@ -337,17 +337,17 @@ ENTRY(empty_bad_pmd_table) 


.org 0xa000

ENTRY(level3_physmem_pgt)

	.quad	0x0000000000105007		/* -> level2_kernel_pgt (so that __va works even before pagetable_init) */

	.quad	0x0000000000005007 + __PHYSICAL_START	/* -> level2_kernel_pgt (so that __va works even before pagetable_init) */



	.org 0xb000

#ifdef CONFIG_ACPI_SLEEP

ENTRY(wakeup_level4_pgt)

	.quad	0x0000000000102007		/* -> level3_ident_pgt */

	.quad	0x0000000000002007 + __PHYSICAL_START	/* -> level3_ident_pgt */

	.fill	255,8,0

	.quad	0x000000000010a007

	.quad	0x000000000000a007 + __PHYSICAL_START

	.fill	254,8,0

	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */

	.quad	0x0000000000103007		/* -> level3_kernel_pgt */

	.quad	0x0000000000003007 + __PHYSICAL_START	/* -> level3_kernel_pgt */

#endif



	.data

include/asm-x86_64/page.h

+4 −2
Original line number Diff line number Diff line
@@ -64,12 +64,14 @@ typedef struct { unsigned long pgprot; } pgprot_t; 
#define __pgd(x) ((pgd_t) { (x) } )

#define __pgprot(x)	((pgprot_t) { (x) } )



#define __START_KERNEL		0xffffffff80100000UL

#define __PHYSICAL_START	((unsigned long)CONFIG_PHYSICAL_START)

#define __START_KERNEL		(__START_KERNEL_map + __PHYSICAL_START)

#define __START_KERNEL_map	0xffffffff80000000UL

#define __PAGE_OFFSET           0xffff810000000000UL



#else

#define __START_KERNEL		0xffffffff80100000

#define __PHYSICAL_START	CONFIG_PHYSICAL_START

#define __START_KERNEL		(__START_KERNEL_map + __PHYSICAL_START)

#define __START_KERNEL_map	0xffffffff80000000

#define __PAGE_OFFSET           0xffff810000000000

#endif /* !__ASSEMBLY__ */

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